The present invention relates to an improvement in a walk-behind, self-propelled working machine which is maneuvered by an operator walking behind and using its handle while the working machine is running.
A conventional walk-behind, self-propelled working machine is disclosed, for example, in Japanese Utility Model Post-Exam Publication No. HEI-5-13140 entitled xe2x80x9cOperating System for Grass Cutting Machine.xe2x80x9d
Conventional working machine has a body, a pair of rear wheels as driving wheels provided at the body, a grass cutter, an engine for driving these components, and a hydraulic transmission interposed between the engine and the pair of rear wheels. This working machine is a walk-behind, self-propelled grass cutting machine having operating left and right pipes extending from a rear end of the body in a rearward and upward direction.
The above working machine has a U-shaped handle with a handle grip integrally provided extending between the top end of the left pipe and the top end of the right pipe. A shift lever is mounted to a longitudinally middle part of the left pipe. A cutter operating lever is rotatably mounted to the top end of the left pipe. A U-shaped neutral lever is rotatably mounted at its both ends to the top ends of the left and right pipes.
Gripping the cutter operating lever with the handle turns on a clutch interposed between an output shaft of the engine and the cutter, thereby transmitting driving force of the engine to the cutter for grass cutting operation. Gripping the neutral lever with the handle operates the hydraulic transmission, thereby rotating the pair of rear wheels and propelling the working machine forward. Swinging the shift lever back and forth controls the hydraulic transmission, adjusting the rotational speed of the pair of rear wheels, and thereby adjusting the driving speed of the working machine.
In a general method of using the above grass cutting machine, the shift lever is first operated to adjust the driving speed of the pair of rear wheels prior to the start of grass cutting operation, and then the cutter operating lever and the neutral lever are operated to perform grass cutting operation. Under relatively stable grass cutting conditions in which only grass is grown on flat grounds, for example, such a general method of use is satisfactory.
However, grass cutting conditions are not always stable. In some cases, for example, grass is grown on rough grounds or on grounds with flower beds, garden rocks, or garden trees. In such an unstable place, grass cutting conditions vary frequently. This requires frequent change of the driving speed of the grass cutting machine for beautiful finish of grass cutting.
For varying the driving speed of the grass cutting machine during operation, there are two methods as follows:
A first method comprises taking off the right hand gripping the handle while propelling the grass cutting machine and cutting grass, and swinging the shift lever with the right hand to adjust the hydraulic transmission. This method changes speed during driving, forcing an operator to take an uncomfortable posture due to operation of the handle with only the left hand while operating the shift lever with the right hand. This requires skill in operating the lever so as not to adversely affect completion of the cutting without leaving grass to be cut or cutting grass unevenly.
The second method comprises temporarily stopping the grass cutting machine every time grass cutting conditions vary, adjusting the hydraulic transmission with the shift lever, and thereafter propelling the grass cutting machine. This method repeats the driving and topping of the grass cutting machine under varying grass cutting condition, thereby reducing operating efficiency.
The present invention provides a walk-behind, self-propelled working machine which allows an operator to easily adjust its driving speed while driving the working machine in a comfortable posture.
According to an aspect of the present invention, there is provided a walk-behind, self-propelled working machine, which comprises: a body; a drive source provided at the body; a pair of driving wheels provided at the body and driven by the drive source; a working tool provided at the body and driven by the drive source; a continuously variable transmission interposed between the drive source and the pair of driving wheels; an operating handle extending from a rear end of the body in a rearward and upward direction; an operation switching lever provided at the handle, for transmitting or interrupting driving force outputted from the drive source to the working tool; a drive switching lever provided at the handle, for operating the continuously variable transmission in order to switch the pair of driving wheels from a halt condition to a high-speed advancement condition; and a speed adjusting rotary control for adjusting the continuously variable transmission in order to adjust the rotational speed of the driving wheels; wherein, the operation switching lever and the drive switching lever are independently provided in the vicinity of a grip of the handle; and the speed adjusting rotary control is provided on one side of the handle in the vicinity of the drive switching lever.
In this invention, the speed adjusting rotary control is provided on the side of the handle in the vicinity of the drive switching lever. That is, the speed adjusting rotary control is disposed near a hand of an operator steering the walk-behind, self-propelled working machine, and the speed adjusting rotary control is rotated to adjust the driving speed of the walk-behind, self-propelled working machine. Specifically, in order to adjust the driving speed of the walk-behind, self-propelled working machine while driving the working machine, an operator continuously grips the drive switching lever together with the handle grip with one hand, rotating the rotary control positioned in the vicinity of the drive switching lever with the other hand which was taken off the grip. Thus the operation switching lever is operated with one hand while the rotary control is operated with the other hand, which increases operability in adjusting the driving speed.
Further, in the present invention, in order to adjust the driving speed while driving the working machine, an operator only moves a hand from the grip of the handle near at hand to the vicinity of the drive switching lever on the side of the handle to operate the speed adjusting rotary control. This results in reduced moving range of the hand. In addition, the operation of only rotating the speed adjusting rotary control reduces the operating range of the hand. As a result, the driving speed of the walk-behind, self-propelled working machine is easily adjusted while the operator drives the working machine in a comfortable steering posture, resulting in improved workability.
Furthermore, since the speed adjusting rotary control is provided on the side of the handle, the speed adjusting rotary control is rotated with a hand put over the side of the handle, eliminating the need for moving both hands off the handle.
In the present invention, the operation switching lever and the drive switching lever are swingably mounted to the handle via left and right support shafts, the operation switching lever has an operating part provided in either of left and right positions with respect to the longitudinal center of the body, and the speed adjusting rotary control is rotatably mounted on one of the support shafts supporting the drive switching lever, being positioned opposite to the operating part of the operation switching lever.
Arranging the drive switching lever and the speed adjusting rotary control in a single place reduces the size and the number of components of peripheral mechanisms of the drive switching lever and the speed adjusting rotary control, preventing peripheral part of the handle from becoming larger and reducing the dimension of the body width. This facilitates operations in narrow working space.